Figure 5.

Dissociation of membrane-bound ¹²⁵I-labeled wild-type and mutant toxins. Gypsy moth BBMV (20 μg per 100 μl) was incubated with 1 nM labeled toxins (association reaction) for 1 h. At the end of association reaction, 100 nM concentration of corresponding nonlabeled toxin was added to the test samples, and incubation (postbinding) was stopped at different time intervals. Nonspecific binding was obtained by incubating the labeled toxin with BBMV in the presence of a 1000-fold excessive corresponding nonlabeled toxin, and the value was subtracted from the total binding. (Inset) BBMV-bound labeled toxins at the end of association binding were resolved on SDS/10% PAGE and autoradiographed. The amounts of DF-1, N372A, CryIAb, and D3 toxins bound to the vesicles were 6050, 2200, 1390, and 321 cpm, respectively.